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如何正确选择投影屏幕
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《电化教育研究》 北大核心 1999年第3期95-95,共1页
正确选择屏幕的四个主要步骤是:(1)选择屏幕类型:您选择的类型应是最适合您的具体使用需要的。例如:需要前投影幕可选择挂墙的类型或天花板的装嵌类型,而且还有手动、电动的规格;需要后投影幕的可选择硬幕或软幕。总的来说,如... 正确选择屏幕的四个主要步骤是:(1)选择屏幕类型:您选择的类型应是最适合您的具体使用需要的。例如:需要前投影幕可选择挂墙的类型或天花板的装嵌类型,而且还有手动、电动的规格;需要后投影幕的可选择硬幕或软幕。总的来说,如果需要固定位置的投影场地,那么墙挂... 展开更多
关键词 亮度增益 正确选择 投影屏 投影机 防霉 屏幕面 屏幕尺寸 反射率 屏幕类型 三脚支架
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警惕计算机视力综合征
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作者 刘为 《当代护士(中旬刊)》 1999年第12期52-52,共1页
你刚刚工作了10个小时,大多数时间又是坐在计算机屏幕面前,你的眼睛感到刺痛而且疲劳,你的头也很疼,可能你已感到双眼模糊了。 这种情况对很多人来说都不陌生,这就是计算机视力综合征(CVS)。
关键词 计算机 综合征 机视 屏幕面 光过敏症 过度使用 注意力 边缘模糊 听说过 疲劳感
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Intention and automaticity toward physical and sedentary screen-based leisure activities in adolescents:A profile perspective 被引量:1
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作者 Gonzalo Marchant Guillaume Chevance Julie Boiché 《Journal of Sport and Health Science》 SCIE 2018年第4期481-488,共8页
Purpose: Physical activity (PA) and sedentary behavior (SB) are increasingly considered independent health behaviors. Additionally, current research suggests that both controlled and automatic determinants accoun... Purpose: Physical activity (PA) and sedentary behavior (SB) are increasingly considered independent health behaviors. Additionally, current research suggests that both controlled and automatic determinants account for their adoption. The purpose of this article was to identify intention-automaticity profiles toward PA and screen-based SB and to examine how those profiles are associated with different behavioral patterns. Method: Two cross-sectional studies based on self-report questionnaires were conducted with French high school students (Study 1: n = 198; Study 2: n = 185). Results: In all, 4 distinct motivational profiles appeared. The first 3 clusters emerged in both studies: "PA" (high levels of automaticity and intention for PA, low levels of automaticity and intention for screen-based SB); "screen" (high levels of automaticity and intention for screen-based SB, low levels of automatieity and intention for PA), and "mixed" (high levels of all variables), whereas the fourth cluster was observed only in Study 2: "high control" (below-mean levels of automaticity, high levels of intention toward both PA and screen-based SB). Adolescents with a screen profile displayed the least healthy behavioral pattern, whereas those in the PA profile demonstrated the most favorable behaviors. Conclusion: Future research is needed to extend these results to other populations using complementary assessment methods of automatic psychological processes and PA and SB behaviors.2018 Published by Elsevier B.V.on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license.(http://creativecommons.org/licenses/by-nc-nd/4.0/). 展开更多
关键词 Active lifestyle Cluster analysis Control Dual process EXERCISE Habit motivation Physical activity
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Screening efficiency and screen length of a linear vibrating screen using DEM 3D simulation 被引量:19
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作者 Wang Guifeng Tong Xin 《Mining Science and Technology》 EI CAS 2011年第3期451-455,共5页
The effect of screen length on the screening efficiency of particles is studied under various single parameter conditions including frequency, amplitude, vibration angle, and screen inclination. The Discrete Element M... The effect of screen length on the screening efficiency of particles is studied under various single parameter conditions including frequency, amplitude, vibration angle, and screen inclination. The Discrete Element Method (DEM) has been used to simulate the screening process. A functional relationship between screening efficiency and screen length is established. It is shown that screening efficiency and screen length have a complicated exponential relationship. Relationships between them are profoundly discussed and conclusions are easily drawn: low values of the parameters do not benefit screening; screening efficiency generally increases with screen length; screening efficiency reaches a plateau when these parameters are in range frequently encountered in practical applications. 展开更多
关键词 Screen lengthScreening efficiency Discrete element method
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Reflecting and transmitting effect of a planar unidirectionally conducting screen
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作者 鄂鹏 江滨浩 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第2期242-246,共5页
The reflecting and transmitting effects of a planar unidirectionally conducting screen are analyzed based on the accurate closed-form expression for electric field of an arbitrarily oriented electric dipole.For a dipo... The reflecting and transmitting effects of a planar unidirectionally conducting screen are analyzed based on the accurate closed-form expression for electric field of an arbitrarily oriented electric dipole.For a dipole oriented along the wire elements of the screen,the screen acts as a perfectly electrically conducting plane.For a dipole perpendicular to the wire elements,the fields reflected by the screen can be interpreted as the contribution of an image dipole and image transmission-line current source,while the transmitted field is arisen from image transmission-line source.The expressions of related surface waves are derived and can be compared with previous results. 展开更多
关键词 electromagnetic fields unidirectionally conducting screen reflection and transmission electric dipole
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Efficient page layout analysis on small devices
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作者 Eun-jung HAN Chee-onn WONG +2 位作者 Kee-chul JUNG Kyung-ho LEE Eun-yi KIM 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第6期800-804,共5页
Previously we have designed and implemented new image browsing facilities to support effective offiine image contents on mobile devices with limited capabilities: low bandwidth, small display, and slow processing. In... Previously we have designed and implemented new image browsing facilities to support effective offiine image contents on mobile devices with limited capabilities: low bandwidth, small display, and slow processing. In this letter, we fulfill the automatic production of cartoon contents fitting small-screen display, and introduce a clustering method useful for various types of cartoon images as a prerequisite stage for preserving semantic meaning. The usage of neural networks is to properly cut the various forms of pages. Texture information that is useful for grayscale image segmentation gives us a good clue for page layout analysis using the multilayer perceptron (MLP) based x-y recursive algorithm. We also automatically frame the segment MLP using agglomerative segmentation. Our experimental results show that the combined approaches yield good results of segmentation for several cartoons. 展开更多
关键词 Efficient page layout analysis MLP-based segmentation Mobile devices Image segmentation Neural network
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