In Physics Education,Perception Matters

Student difficulties in science learning are frequently attributed to misconceptions about scientific concepts. We argue that domain‐general perceptual processes may also influence students' ability to learn and demonstrate mastery of difficult science concepts. Using the concept of center of gravity (CoG), we show how student difficulty in applying CoG to an object such as a baseball bat can be accounted for, at least in part, by general principles of perception (i.e., not exclusively physics‐based) that make perceiving the CoG of some objects more difficult than others. In particular, it is perceptually difficult to locate the CoG of objects with asymmetric‐extended properties. The basic perceptual features of objects must be taken into account when assessing students' classroom performance and developing effective science, technology, engineering, and mathematics (STEM) teaching methods.     

Representing How Rabbits Quack and Competitors Act: Limits on Preschoolers' Efficient Ability to Track Perspective

This study investigated whether humans have two mind‐reading systems whereby the efficient system, unlike the flexible system, is naturally limited. There were two experiments and the first included adults as well as children (3‐ to 4‐year‐olds; total N = 128). In Experiment 1, all groups efficiently gazed in anticipation of an agent's beliefs about object location but not object identity (an ambiguous figure). In Experiment 2, children showed limits in anticipating a competitive agent's action in terms of his perspective on what is desirable. Flexibility in verbally predicting agents' actions across contexts developed with age. Convergence on signature limits across different ages and methods suggests that indirect anticipations involve minimal mind reading, whereas direct predictions tap a refined understanding of perspective.     

Success,failure and emotions: examining the relationship between performance feedback and emotions in diagnostic reasoning

Students experience a variety of emotions following achievement outcomes which stand to influence how they learn and perform in academic settings. However, little is known about the link between student outcome emotions and dimensions of performance feedback in computer-based learning environments (CBLEs). Understanding the dynamics of this relationship is particularly important for high-stakes, competency-based domains such as medical education. In this study, we examined the relationship between medical students’ (N = 30) outcome emotion profiles and their performance on a diagnostic reasoning task in the CBLE, BioWorld. We found that participants could be organized into distinct emotion groups using k-means cluster analyses based on their self-reported outcome emotion profiles: an expected positive emotion cluster and negative emotion cluster and an unexpected low intensity emotion cluster. A clear relationship was found between emotion clusters and diagnostic performance such that participants classified to the positive emotion cluster had the highest performance; those classified to the negative emotion cluster had the lowest performance; and those classified to the low intensity emotion cluster had performance outcomes that fell between the other two. Our discussion focuses on the theoretical implications of emotion classification and design recommendations for learning environments and emotional interventions in computer-based contexts.     

The North Wind and the Sun

The north wind and the sun are good friends.But one day they quarrelabout something. “I am stronger than you.”the cold north wind says.“Indeed you arenot.I’m stronger than you,”answers the soft,warm sun. Just then they see a man walking along the road. “I can get that man’s hat off his head,”the wind says.     

Tagging and searching: Search retrieval effectiveness of folksonomies on the World Wide Web

Many Web sites have begun allowing users to submit items to a collection and tag them with keywords. The folksonomies built from these tags are an interesting topic that has seen little empirical research. This study compared the search information retrieval (IR) performance of folksonomies from social bookmarking Web sites against search engines and subject directories. Thirty-four participants created 103 queries for various information needs. Results from each IR system were collected and participants judged relevance. Folksonomy search results overlapped with those from the other systems, and documents found by both search engines and folksonomies were significantly more likely to be judged relevant than those returned by any single IR system type. The search engines in the study had the highest precision and recall, but the folksonomies fared surprisingly well. Del.icio.us was statistically indistinguishable from the directories in many cases. Overall the directories were more precise than the folksonomies but they had similar recall scores. Better query handling may enhance folksonomy IR performance further. The folksonomies studied were promising, and may be able to improve Web search performance.     

Extended-state-observer-based output feedback adaptive control of hydraulic system with continuous friction compensation

This paper presents an extended state observer-based output feedback adaptive controller with a continuous LuGre friction compensation for a hydraulic servo control system. A continuous approximation of the LuGre friction model is employed, which preserves the main physical characteristics of the original model without increasing the complexity of the system stability analysis. By this way, continuous friction compensation is used to eliminate the majority of nonlinear dynamics in hydraulic servo system. Besides, with the development of a new parameter adaption law, the problems of parametric uncertainties are overcome so that more accurate friction compensation is realized. For another, the developed adaption law is driven by tracking errors and observation errors simultaneously. Thus, the burden of extended state observer to solve the remaining uncertainties is alleviated greatly and high gain feedback is avoided, which means better tracking performance and robustness are achieved. The designed controller handles not only matched uncertainties but also unmatched dynamics with requiring little system information, more importantly, it is based on output feedback method, in other words, the synthesized controller only relies on input signal and position output signal of the system, which greatly reduces the effects caused by signal pollution, measurement noise and other unexpected dynamics. Lyapunov-based analysis has proved this strategy presents a prescribed tracking transient performance and final tracking accuracy while obtaining asymptotic tracking performance in the presence of parametric uncertainties only. Finally, comparative experiments are conducted on a hydraulic servo platform to verify the high tracking performance of the proposed control strategy.     

一个工程系的创办和ABET评估认证:东卡罗来纳大学案例分享

从受评方的角度,总结了创办一个工程系和准备美国ABET工程技术专业认证的整个过程.首先对ABET和东卡罗来纳大学工程系进行必要的介绍,然后完整讲述了为准备ABET认证的组织协调,人员配置,评估计划书的制定,受评方与ABET的沟通,以及评估小组进校考察的前后过程.并且提供了课程-产出映射关系的具体实例.希望为中国工程教育同行今后准备此类认证工作提供实用的参考.     

Impacts of Globalization on E-Commerce Use and Firm Performance: A Cross-Country Investigation

This article develops and tests a model examining the relationship between firm globalization, scope of e-commerce use, and firm performance, using data from a large-scale cross-country survey of firms from three industries. We find that globalization leads to both greater scope of e-commerce use and improved performance, measured as efficiency, coordination, and market impacts. Scope of e-commerce use also leads to greater firm performance of all three types. Globalization has differential effects on B2B and B2C e-commerce, however, such that highly global firms are more likely to do B2B but less likely to do B2C. Our findings provide support for Porter's (1986) thesis that upstream business activities (namely, B2B) are more global while downstream business activities (B2C) are more local or multidomestic.     

Ten Years of Puzzling about Audience Awareness

The decisions evaluators make regarding how to work with teachers through the annual evaluation process can have a positive impact on teacher growth and student learning. In this article, the author examines the quality of feedback and how administrators use and provide this feedback to teachers through the evaluation process. What constitutes quality feedback? How does quality feedback support teachers' instruction? How can the supervision and evaluation process offer both teachers and administrators an opportunity to work together to improve student learning? The evaluation process should support the goal of maintaining a high level of quality instruction. In the end, the goal is to increase student learning by improving the effectiveness of teaching.     

Digital redesign tracker for cascaded analog systems with state saturation and external loads

This paper presents a newly developed digital redesign control scheme with a weighted switching strategy and output-reference tracking, for a cascaded analog system with state saturation and external loads. The proposed method improves the generally poor transition response and output deviation caused by state-saturation constraint and external loads. It replaces an existing or theoretically well-designed analog controller with state saturation, by a digital controller with almost identical performance.