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11.
Zygmunt Rymuza 《Wear》1980,58(1):97-102
The effect of oil spreading on plastic bushes on the wear of steel-polymer precision pivot bearings was investigated. Analysis of oil spreading allowed a comparative evaluation of the surface free energy of the various polymers used as bush materials to be made. Correlation was found between the influence of lubrication on the wear of the bearings and the spreading velocity of the oil. 相似文献
12.
We describe a new approach to measuring DNA hybridization using surface plasmon-coupled emission (SPCE). Excited fluorophores are known to couple with surface oscillations of electrons in thin metal films, typically 50 nm thick silver on a glass prism. These surface plasmons then radiate into the glass at a sharply defined angle determined by the emission wavelength and the optical properties of the glass and metal. This radiation has the same spectral profile as the emission spectrum of the fluorophores. We studied the emission due to Cy3-labeled DNA oligomers bound to complementary unlabeled oligomers which were themselves bound to the metal surface. Hybridization resulted in SPCE due to Cy3-DNA into the prism. Directional SPCE was observed whether the sample was illuminated from the sample side or through the glass substrate at the surface plasmon angle for the excitation wavelength. A large fraction of the total potential emission is coupled to the surface plasmons resulting in improved sensitivity. When illuminated through the prism at the surface plasmon angle, the sensitivity is increased due to the enhanced intensity of the resonance evanescent field. It is known that SPCE depends on proximity to the silver surface. As a result, changes in emission intensity are observed due to fluorophore localization even if hybridization does not affect the quantum yield of the fluorophore. The use of SPCE resulted in suppression of interfering emission from a noncomplementary Cy5-DNA oligomers due to weaker coupling of the more distant fluorophores with the surface plasmons. We expect SPCE to have numerous applications to nucleic acid analysis and for the measurement of bioaffinity reactions. 相似文献
13.
The natural-convectioe flow of a viscous and heat-conducting fluid in systems of cylinders, arranged vertically in regular patterns, is studied. The aim of the study is to determine the conditions of stability of the fluid when heated from below and cooled from above. In particular, the influence of geometry and thermal properties of the system on the free stationary convection are studied. A new way of calculating the free convection threshold is proposed. The final results are analytical formulas for determining the critical Rayleigh numbers for the studied forms of flow and graphs, showing the dependency of these numbers on the geometrical parameters of arrays. 相似文献
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In this paper, we report on the design of a protocol for transparent, location-independent access in mobile systems. The protocol, termed by us Mobile Client/Server Protocol (MCSP) is an implementation of a communication layer on a mobile host and a stationary machine within the wireline network, and provides middleware functionality. The MCSP supports communication services through the client/server paradigm to transaction-oriented applications distributed between the mobile and a set of service and information brokers. To support the mobile and the wireless environment, a surrogate process is created within the fixed network to perform operations on behalf of the mobile within the fixed network. The MCSP then loosely couples the communicating entities, thus reducing the overhead associated with handoffs and disconnects, so characteristic of the mobile environment. Of particular interest is the application of the MCSP to location-based services, for example, the Intelligent Vehicle Highway Systems [1]. 相似文献
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This paper deals with the problem of ultimate load-carrying capacity of thin-walled sections subject to combined load. That has direct implementation in sizing and design of thin-walled structures. It is solved using the ultimate strength method based on the theory of plastic analysis of structures. It is assumed that the elastic strains are negligible in comparison to the plastic strains and that justifies the application of a fully plastic model. The following problems have to be analyzed before the sizing and design is completed:
- • Load vectors and load components
- • Locations of the plastic neutral axes
- • The surface of ultimate strength
18.
Zygmunt Pizlo Azriel Rosenfeld Isaac Weiss 《Computer Vision and Image Understanding》1997,65(3):425-433
We address the problem of a geometrical model of vision. This problem is interesting for at least two reasons. First, any theory of vision (human or computer) must decide which geometry should be used to represent perceived objects (e.g., Euclidean vs projective). We believe that this representation should be compatible with geometrical properties of the imaging device (eye or camera). Second, the analysis of geometrical properties of vision will examine the usefulness of standard geometries and can lead to progress in mathematics itself. We analyze the geometry of image formation and show that human vision appears to involve a new branch of geometry whose properties are quite different from the properties of traditional geometries. We formulate these properties and use them to derive models of shape perception. Finally, we provide perceptual interpretations for our theoretical analyses. 相似文献
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