共查询到18条相似文献,搜索用时 125 毫秒
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在间歇式高速摄影机小的间歇输片机构中,抓片机构类型目前仍然占主导地位。这种类型的高速摄影机虽然机构较为复杂,工艺性差,但它具有质量稳定可靠,综合性能好,多用性好等优点,所以目前仍广泛应用。曲柄摇杆机构又是在抓片机构中采用较多的一种机构型式。下面我们对此种结构进行讨论。 相似文献
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滚环机构(Rollinq Loop Mechanism)是一种采用新工作原理的间歇输片机构。本文在分析这一系统基本工作原理的基础上,推导了机构工作角、光效系数、片环曲线方程,并给出了片带运动段上各点的速度与加速度的计算方法。 在给定机构主要设计参数后,利用本文提出的方法,在电子计算机上可以迅速求解 相似文献
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GS240/35高速电影摄影机是一种间歇式高速电影摄影机,频率可达240幅/秒,使用35毫米胶片,画幅大小为22×18毫米。间歇运动的主要部件——抓片机构的结构和特性,直接影响摄影机的频率和画幅质量。 相似文献
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对摄影机的主要系统组成、工作原理和性能指标进行了简要介绍.论述了作为摄影机核心部件的曲柄摇杆式输片机构的类型、设计和动力学分析.为了适应两种不同的画幅尺寸要求(四片孔画幅尺寸为50×18.8 mm,八片孔为50×36 mm),设计并研制了两套输片机构.它们的接口形式和结构完全相同,可以方便用户快速更换,达到一机多用的目的.在该摄影机的研制过程中探索性地应用了虚拟制造技术,解决了由摄影频率提高而引起的一系列技术难题.虚拟制造的应用不仅提高了设计制造水平,同时也缩短了研制周期,降低了研制成本.实际应用证明了70 mm间歇式高速摄影机的研制是成功的. 相似文献
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《Journal of Electrostatics》2007,65(7):438-444
A new paper separation and feed mechanism is proposed to realize a highly reliable paper handling system for printers and copiers. The paper-separation system consisted of a pair of parallel electrodes and a paper pile between the electrodes. Electrostatic separation of a piece of paper was possible from the top of the pile when the applied voltage exceeded the threshold needed to generate an electrostatic force larger than the weight of the paper. The threshold voltage was on the order of several kilovolts, and it agreed with the numerical value calculated using the finite element method (FEM) for the electrostatic field. Based on these basic investigations, a prototype mechanism for paper separation and feeding was constructed. It consisted of a roller-type separation electrode coated with an insulating film, a biased charger roller in contact with the separation roller to charge the insulating film on the separation roller, a ground electrode, and a paper pile situated between the electrodes. When an electrostatic field was applied between the biased charger roller and the ground electrode on which the paper pile was mounted, only the top sheet of paper separated, adhering electrostatically to the roller. The sheet was then fed rotating the separation roller. Using this system, reliable paper separation and feed was realized and a feed speed over 600 mm/s was demonstrated. 相似文献
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In thin films of liquid falling over an inclined surface random (or non-random) small dry spots shut and disappear or expand into the large-scale dry spots depending on the initial spot sizes and parameters of the liquid film. On consideration of the gravity forces, inertial forces of the film and surface tension, affecting the elements of a roller surrounding the dry spot, we have formulated a criterion, which helped us to answer the following question: if this spot shuts or not? This criterion includes the numbers of Bond and Reynolds and the contact wetting angle as the determining parameters. It is generalization of the known Hartley — Murgatroid criterion, which allows determination of the zone of falling film metastability, i. e., determination of the critical film thickness, below whose value the formation of stable dry spots is possible. It is shown that the critical values of parameters of the initial dry spot depend on the shape and sizes of a roller surrounding this spot. 相似文献
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The current-voltage characteristics of metal-insulator-metal microdevices fabricated with electron-beam evaporated vanadium
pentoxide films have been studied in order to understand the electrical transport mechanism in these films. The dependence
of transport properties on various factors such as film thickness, substrate temperature, and applied field, has been established.
The results revealed that the electrical transport follows a Schottky-type mechanism at lower electrical fields and a Poole-Frenkel-type
at higher electrical fields than 2×106 V/m. 相似文献
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Metal/dielectric composite films consisting of metal objects located in dielectric matrix are investigated by computer simulation. The complete computer experiment is devoted to the study of correlation between structural properties and electrical characteristics of composite films. In the present analysis transport properties of films are calculated near the metal-dielectric transition when the basic mechanism of charge transport is the tunnel effect. The conductivity of composite film is disseminated into individual percolation paths influenced by object arrangements in the composite film. 相似文献
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由于纳米结构具有极高的表体比,声子-表面散射机制对声子的热输运性质起到关键作用.提出了表面低配位原子对声子的散射机制,并且结合量子微扰理论与键序理论推导出该机制的散射率.由于散射率正比于材料的表体比,这种散射机制对声子输运的重要性随着纳米结构尺寸的减小而增大.散射率正比于声子频率的4次方,所以这种散射机制对高频声子的作用远远强于对低频声子的作用.基于声子玻尔兹曼输运方程,计算了硅纳米薄膜和硅纳米线的热导率,发现本文模型比传统的声子-边界散射模型更接近实验值.此发现不仅有助于理解声子-表面散射的物理机制,也有助于应用声子表面工程调控纳米结构的热输运性质. 相似文献