Application of the Bayes＇ theory to the failure rate evaluation of electrical apparatus

The Weibull distribution has been widely used in reliability fields. A mixed Weibull distribution represents a population that consists of several Weibull subpopulations. In this paper, a new approach which combines the least-squares method with Bayes＇ theorem, takes advantage of the parameter estimation for single Weibull distribution is developed to estimate the parameters of each subpopulation. The estimates given by this paper also satisfy the maximum likelihood equation. The estimates of the failure rate of the mixed Weibull population are given. An actual test data is computed by using the proposed method. The Kolmogorov-Smirnov goodness-of-fit test turns out that the proposed method yields more accurate result.     

A new patch antenna with metamaterial cover

INTRODUCTION Investigation of metamaterials is currently one of the most active frontiers in engineering and physics. Metamaterials are also called backward-wave mate- rials, double-negative materials, or left-handed mate- rials. Left-handed materials were proposed by Vese- lago (1968). The applications of metamaterials are widely spread in many fields (Pendry, 2000; Grbic and Eleftheriades, 2003; Foteinopoulou et al., 2003), such as imaging apparatus, planar light wave circuits, optica…     

Development and validation of a model for predicting wheel wear in high-speed trains

In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules: a multi-body model implemented with the commercial multi-body software SIMPACK to evaluate the dynamic response of the vehicle and track; a local contact model based on Hertzian theory and a novel method, named FaStrip (Sichani et al., 2016), to calculate the normal and tangential forces, respectively; a wear model proposed by the University of Sheffield (known as the USFD wear function) to estimate the amount of material removed and its distribution along the wheel profile; and a smoothing and updating strategy. A simulation of the wheel wear of the high-speed train CRH3 in service on the Wuhan-Guangzhou railway line was performed. A virtual railway line based on the statistics of the line was used to represent the entire real track. The model was validated using the wheel wear data of the CRH3 operating on the Wuhan- Guangzhou line, monitored by the authors’ research group. The results of the predictions and measurements were in good agreement.     

HOW CAN SCIENCE HELP US CARE FOR NATURE? HERMENEUTICS,FRAGILITY, AND RESPONSIBILITY FOR THE EARTH

In this review essay, Clarence Joldersma argues for a novel role for science in developing an affirmative answer to his title question, “How can science help us care for nature?” He does so in dialogue with Clare Palmer's edited volume, Teaching Environmental Ethics, Dirk Postma's Why Care for Nature? and Michael Bonnett's Retrieving Nature. Joldersma suggests that although each book can help address the issue of how to teach students to care for nature, he parts company with their stance that we must go beyond science to develop a metaphysics of nature adequate to the task. Relying on the same Heideggerian framework as Postma and Bonnett, Joldersma comes to a different assessment of the role of science. He does so by arguing for a hermeneutic understanding of science as social practice and by claiming that science so construed can disclose the planet as earth (in the later Heidegger's sense), for which we owe thanks. This disclosure reveals earth as that which is fragile and for which we are responsible.     

Anxiety and the Use of Alcohol‐Related Protective Behavioral Strategies

Protective behavioral strategies (PBS) are useful skills for reducing the negative consequences of alcohol. The moderating effects of anxiety on the relationship between 3 different types of PBS and negative consequences were examined among students accessing college counseling services. Results revealed a significant interaction between anxiety and strategies while drinking, suggesting that these simple strategies may be particularly beneficial among students who drink heavily and experience high levels of anxiety. Implications for counseling centers are discussed.     

The effect of teacher education programs on future elementary mathematics teachers’ knowledge: a five-country analysis using TEDS-M data

This article addresses the problem of how opportunities to learn in teacher education programs influence future elementary mathematics teachers’ knowledge. This study used data collected for the Teacher Education and Development Study in Mathematics (TEDS-M). TEDS-M measured the mathematics content knowledge (MCK) and the mathematics pedagogical content knowledge (MPCK) of future teachers in their final year in teacher preparation programs. The purpose of this study is to explore whether elementary teaching candidates’ MCK and MPCK are associated with their opportunities to learn in mathematics courses and mathematics methods courses in five countries. The results showed that opportunities to learn in some teacher preparation components are more important than in other components.     

EPR-RCGA-based modelling of compression index and RMSE-AIC-BIC-based model selection for Chinese marine clays and their engineering application

The compression index is a key parameter in the field of soft clay engineering. In this paper, we propose an improved method for correlating the compression index with the physical properties of intact Chinese marine clays that are involved in many construction projects in coastal regions in China. First, the compression index and some common physical properties of clays from 21 regions along the Chinese coast are extracted from the literature. Then, a basic regression analysis for the compression index using the natural water content and Atterberg limits is conducted. To improve the correlation performance, an evolutionary polynomial regression (EPR) and real coded genetic algorithm (RCGA) combined technique is adopted to formulate different equations involving different numbers of variables. An optimal correlation using only natural water content and liquid limit as input parameters is finally selected according to the root mean square error (RMSE), Akaike’s information criterion (AIC), and Bayesian information criterion (BIC). The proposed correlation is evaluated and shown to perform better than existing empirical correlations in predicting the compression index for all selected Chinese marine clays. This correlation is validated to be reliable and applicable to engineering applications through the prediction of the properties of an embankment on the southeast coast of China using finite element method. All comparisons show that the EPR and RCGA combined technique is powerful for correlating the compression index with the physical properties of the clay, and that model selection by RMSE, AIC, and BIC is effective. The proposed correlation could be used to update current formulations, and is applicable to engineering design in coastal regions of China.     

Scaffolding reflection and articulation of scientific explanations in a data-rich,project-based learning environment: An investigation of progress portfolio

In this study, we examined how learners developed scientific explanations about light with the assistance of various technology-based scaffolds. The study emphasis was on scaffolding processes of reflection and articulation. We used a content-neutral software program (Progress Portfolio) to create the instructional scaffolds. A qualitative research design was used to investigate two pairs of prospective teachers in a science content course in engineering. Our findings suggested that the computer-based scaffolds used in our study were useful to support articulation, reflection, and revision of explanations, when certain conditions were met. A major theme of our findings relates to interacting effects among learner characteristics, teacher coaching, software scaffolding design, and task characteristics. This material is based on work supported by the National Science Foundation under NSF REC 9980055, which was granted to the second author. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. The authors would like to acknowledge Joe Taylor for his role in the design and implementation of the study.