数字图像分析方法在螺纹检测中的应用

This paper describes the use of computer-aided measurement for external metric screw threads.Thread parameters,including thread pitch,thread angle,pitch giameter and major diameter,were measured with CCD cameras and image analysis software.New technologies such as digital image processing were used to increase the efficiency of measurements.In this study,by reconstructing the toolmaker‘s microscope,the computer-aided semi-automated measuring system was developed,which could evaluate the accuracy of screw thread fpofile.It is concluded that the measuement accuracy is comparable to that of traditional toolmaker‘s microscope method.     

Categories in conflict: Combating the application of an intuitive conception of inheritance with category construction

The idea that characteristics acquired by an organism during its lifetime can be inherited by offspring and result in evolution is a substantial impediment to student understanding of evolution. In the current study, we performed a preliminary examination of how acquiring physical changes in a question prompt may differentially cue intuitive and scientific justifications of inheritance and evolution and how this varies based on how student learned the concept. Middle school students in a suburban northeastern district (N = 314) either learned about evolutionary change with a category construction task (with different levels of feedback support) or completed a worksheet. Three days later students responded to two free response scenarios (one where a physical change is acquired). Responses were coded based on student justifications for either science accuracy or intuitive nature. Specific reasons were coded by justification type with high inter-rater agreement (k > 0.93). Results showed that students were more likely to apply intuitive reasoning when a physical change was acquired (50%) than if the change was behavioral in nature (16%). Additionally, students who completed the category construction task provided significantly more scientifically accurate justifications about inheritance (M = 1.12) than control students (M = 0.47), and significantly less intuitive justifications (M = 0.67) than control (M = 1.13). Finally, category construction produced the most scientific reasoning when feedback was provided. Taken together, these results suggest that intuitive reasoning is differentially applied based on physical organismal changes, intuitive reasoning is less frequent when learning via category construction, and the category construction task is more effective for this population with the inclusion of feedback.     

Feature-positive discriminations during a spatial-search task with humans

During feature-positive operant discriminations, a conditional cue, X, signals whether responses made during a second stimulus, A, are reinforced. Few studies have examined how landmarks, which can be trained to control the spatial distribution of responses during search tasks, might operate under conditional control. We trained college students to search for a target hidden on a computer monitor. Participants learned that responses to a hidden target location signaled by a landmark (e.g., A) would be reinforced only if the landmark was preceded by a colored background display (e.g., X). In Experiment 1, participants received feature-positive training (+←YB/ XA→+/A?/B?) with the hidden target to the right of A and to left of B. Responding during nonreinforced transfer test trials (XB?/YA?) indicated conditional control by the colored background, and spatial accuracy indicated a greater weighting of spatial information provided by the landmark than by the conditional cue. In Experiments 2a and 2b, the location of the target relative to landmark A was conditional on the colored background (+←YA/ XA→+/ ZB→+/ +←C /A?/B?). At test, conditional control and a greater weighting for the landmark’s spatial information were again found, but we also report evidence for spatial interference by the conditional stimulus. Overall, we found that hierarchical accounts best explain the observed differences in response magnitude, whereas spatial accuracy was best explained via spatial learning models that emphasize the reliability, stability, and proximity of landmarks to a target.     

Designing With Multiple Interactives: Five Common Pitfalls

Abstract Interactive museum exhibits are ubiquitous in science centers, and are becoming increasingly popular in art, history and cultural museums. At an interactive exhibit, visitors can act on the exhibit and the exhibit reacts. While there is much theoretical and empirical support for the idea that interactive features promote science learning, we believe that serious design problems can arise if an uncritical “more is better” approach is taken to interactivity. This article describes five common pitfalls of designing exhibits with high levels of interactivity or multiple interactive features: 1) multiple options with equal salience, 2) features allowing multiple users to interfere with one another, 3) options that encourage users to disrupt the phenomenon being displayed, 4) features that make the critical phenomenon difficult to find, and 5) secondary features that obscure the primary feature. Examples of each of the five problems are presented, and possible design solutions are offered.