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1.
Similarity solutions for slender dry patches with thermocapillarity   总被引:2,自引:0,他引:2  
The lubrication approximation is used to investigate slender dry patches in an infinitely wide film of viscous fluid flowing steadily on an inclined plane that is either heated or cooled relative to the surrounding atmosphere. Four non-isothermal situations in which thermocapillary effects play a significant role are considered.Similarity solutions describing a thermocapillary-driven flow with a dry patch that is widening or narrowing due to either gravitational or surface-tension effects on a non-uniformly heated or cooled substrate are obtained, and examples of these solutions, when the substrate temperature gradient depends on the longitudinal coordinate according to a general power law, are presented. When gravitational effects are strong, the solution contains a free parameter, and for each value of this parameter there is a unique solution representing both a narrowing pendent dry patch and a widening sessile dry patch, whose transverse profile has a monotonically increasing shape. When surface-tension effects are strong, the solution also contains a free parameter, and for each value of this parameter there is both a unique solution representing a narrowing dry patch, whose transverse profile has a monotonically increasing shape, and a one-parameter family of solutions representing a widening dry patch, whose transverse profile has a capillary ridge near the contact line and decays in an oscillatory manner far from it.Similarity solutions are also obtained for both a gravity-driven and a constant-surface-shear-stress-driven flow with a dry patch that is widening or narrowing due to thermocapillarity on a uniformly heated or cooled substrate. The solutions in both cases contain a free parameter, and for each value of this parameter there is a unique solution representing both a narrowing dry patch on a heated substrate and a widening dry patch on a cooled substrate, whose transverse profile has a monotonically increasing shape.  相似文献   

2.
Chen YS  Hsu YC 《Applied optics》1994,33(29):6818-6822
One way of testing color vision is with a color-blindness plate (CBP) consisting of a set of brilliant colored dots to form a pattern (a figure) and a set of other colored dots to form a background. Classification of such a type of color image into a pattern and a background with a traditional technique is difficult. Based on a self-organizing feature map and a labeling process as well as spatial distance computation, an effective approach to the segmentation of a CBP image is presented. We describe the principle of a CBP segmentation and then introduce the CBP. The proposed approach is described, and its experimental results are presented. We conclude that the method can segment the CBP image into a pattern and a background successfully.  相似文献   

3.
为了提高并联机床的加工精度,分析了并联机床的动力学特性对加工精度的影响。根据牛顿—欧拉方程,得到并联机床的动力学方程,解得连杆的驱动力;根据杆件轴向伸长量与受力之间的关系,得到连杆的长度误差;以无长度误差的连杆长度为优化目标,用优化的方法,得到动平台的位姿,并与连杆有长度误差时动平台的位姿比较,得动平台的位姿误差;根据刀具在动平台坐标系中位置,得刀具加工位置误差及对被加工零件精度的影响。结果表明:并联机床连杆的长度误差,引起刀具加工位置误差,使被加工零件产生形位误差和尺寸误差;并联机床电主轴偏心引起连杆的长度误差的扰动,产生刀具加工位置的扰动误差,影响被加工零件的表面粗糙度。  相似文献   

4.
The effect of a thin adsorbed film on the fluctuational electromagnetic tangential force of interaction between a moving nanoparticle and a flat solid surface was theoretically studied for the first time in a nonrelativistic approximation. Particular calculations were performed for a metal film on a dielectric and for a dielectric film on a metal. In both cases, the nanoparticle is assumed to be made of a nonmagnetic metal. It is shown that, at a normal temperature, the presence of an adsorbed film may lead to an increase in the tangential friction force by one or two orders of magnitude for a certain relation between the particle distance from the surface and the film thickness. In the case of a dielectric film on a metal substrate, a decrease in the temperature is accompanied by exponential decrease in the viscous friction. For a metal film on a dielectric substrate, the tangential force exhibits a quadratic dependence on the temperature.  相似文献   

5.
Chen Z  Ning R 《Applied optics》2003,42(35):7043-7051
Radon data interpolation is a necessary procedure in computed tomography (CT), especially for reconstruction from divergent beam scanning. In a polar-grid representation, the Radon data of a fanbeam projection are populated on an arc, rather on a radial line. Collectively, the Radon data generated from a fanbeam CT system are unevenly populated: The population becomes sparser as the polar distance increases. In CT reconstruction, the Fourier central slice theorem requires a radial scanline full of Radon data. Therefore the vacant entries of a scanline must be filled by interpolation. In addition, interpolation is also required in polar-to-Cartesian conversion. In this paper we propose a practical interpolation technique for filling the vacant entries by local convex combination. It is a linear interpolant that generates a value for a grid point from the available data lying in its neighborhood, by a weighted average, with the weights corresponding to the inverse distances. In fact, the linear convex combination serves as a general flat-smoothing operation in filling a vacancy. Specifically, this technique realizes a variety of linear interpolations, including nearest-neighbor replication, two-point collinear, three-point triangulation, and four-point quadrilateral, and local extrapolation, in a unified framework. Algorithms and a simulation demonstration are provided.  相似文献   

6.
Duangrit Bunnag     
《设计新潮》2014,(5):55-60
用“人生赢家”来形容Duangrit Bunnag不为过,伦敦AA建筑学院毕业生,在金融危机的谷底逆市创立设计公司,设计亚洲数一数二的漂亮酒店:他开的餐厅,常客名单里有维珍航空创始人RichardBranson:他的公司集群在一个5,000多平方米的旧工厂遗址上,设计公司、餐厅、书店、咖啡馆、家具贩售中心、画廊,店都是他的,地也是他的。  相似文献   

7.
In this paper, we provide what might be regarded as a manifestly covariant presentation of discrete quantum theory. A typical quantum experiment has a bunch of apparatuses placed so that quantum systems can pass between them. We regard each use of an apparatus, along with some given outcome on the apparatus (a certain detector click or a certain meter reading for example), as an operation. An operation (e.g. B(b(2)a(3))(a(1))) can have zero or more quantum systems inputted into it and zero or more quantum systems outputted from it. The operation B(b(2)a(3))(a(1)) has one system of type a inputted, and one system of type b and one system of type a outputted. We can wire together operations to form circuits, for example, A(a(1))B(b(2)a(3))(a(1))C(b(2)a(3)). Each repeated integer label here denotes a wire connecting an output to an input of the same type. As each operation in a circuit has an outcome associated with it, a circuit represents a set of outcomes that can happen in a run of the experiment. In the operator tensor formulation of quantum theory, each operation corresponds to an operator tensor. For example, the operation B(b(2)a(3))(a(1)) corresponds to the operator tensor B(b(2)a(3))(a(1)). Further, the probability for a general circuit is given by replacing operations with corresponding operator tensors as in Prob(A(a(1))B(b(2)a(3))(a(1))C(b(2)a(3))) = ?(a(1))B(b(2)a(3))(a(1))C(b(2)a(3)). Repeated integer labels indicate that we multiply in the associated subspace and then take the partial trace over that subspace. Operator tensors must be physical (namely, they must have positive input transpose and satisfy a certain normalization condition).  相似文献   

8.
A Product–Service System (PSS) is created by combing a tangible product and an intangible service into one integrated offering. Thus, a PSS can be achieved by a production company adding intangible services to a product using a servitisation strategy or by a service company adding a tangible product to a service by means of a productisation strategy. The focus of this paper is on the latter. Our work demonstrates a significant gap in the literature in this area. To address this, we adapt an existing PSS conceptual framework as a means to identify the driving and restraining forces considered by a service company as it explored the possibility of pursuing a PSS productisation strategy. The conceptual framework is applied in an exploratory case study with a 3PL service provider. Application of the framework reveals new driving and restraining forces not previously discussed in the literature. Furthermore, it allows a preliminary quantification of the driving and restraining forces using a force field analysis approach. Our work contributes towards the expansion of the empirical knowledge base in the area of PSS.  相似文献   

9.
Zhang Y  Kachru R 《Applied optics》1996,35(34):6762-6766
An optical novelty filter with phase-conjugate photon echoes is constructed to measure a sudden change in the index of refraction of a transparent medium. This novelty filter is set up as a Michelson interferometer and employs a europium-doped crystal as a phase-conjugate mirror. The filter is sensitive to the sudden change in index of refraction when the phase-conjugate echo experiences a different path length from the first laser excitation pulse in a photon-echo experiment. Using a Pockels cell as a pure phase modulator, we demonstrate that the filter can resolve a sudden phase change occurring on a nanosecond time scale with an accuracy and resolution close to 5°.  相似文献   

10.
Building a three-dimensional (3-D) computer-based representation of a large or complex scene from a set of range images requires assembling the range images so that they are spatially registered. This paper will present a technique for finding a homogeneous transformation between a pair of range images while making use of both range and intensity information obtained using a laser range scanner. A demonstrated application featuring this technique consists of building a 3-D representation of a nuclear dumpsite, which then serves to help control a teleoperated nuclear waste remediation system  相似文献   

11.
主要针对Pd-C高温共晶点复现装置的组成进行介绍,其中包括复现用高温均热炉炉体、温度控制系统、真空泵、充气保护装置、水冷系统、复现用的石墨坩埚、二等B型标准热电偶和Pt-Pd热电偶等。针对石墨坩埚的灌注和共晶点复现过程进行了描述,根据复现的试验数据进行了相应的分析。  相似文献   

12.
It is defined the magnetic interaction energy between two superconductor pieces situated in a magnetic field by using the elastic coupling through the flux lines. On this basis, it is shown that a force between a superconducting material and a source of magnetic field is always repulsive, the force between a ferromagnetic material and a source of magnetic field is always attractive and a force between a normal metal and a source of time-varying magnetic field is always repulsive.  相似文献   

13.
A magnetic vortex is a curling magnetic structure realized in a ferromagnetic disk, which is a promising candidate for a memory cell for future non-volatile data-storage devices. Thus, an understanding of the stability and dynamical behaviour of the magnetic vortex is a major requirement for developing magnetic data-storage technology. Since the publication of experimental proof for the existence of a nanometre-scale core with out-of-plane magnetization in a magnetic vortex, the dynamics of vortices have been investigated intensively. However, a way to electrically control the core magnetization, which is a key for constructing a vortex-core memory, has been lacking. Here, we demonstrate the electrical switching of the core magnetization by using the current-driven resonant dynamics of the vortex; the core switching is triggered by a strong dynamic field that is produced locally by a rotational core motion at a high speed of several hundred metres per second. Efficient switching of the vortex core without magnetic-field application is achieved owing to resonance. This opens up the potentiality of a simple magnetic disk as a building block for spintronic devices such as a memory cell where the bit data is stored as the direction of the nanometre-scale core magnetization.  相似文献   

14.
The properties of a laser beam coupled out of a standard unstable laser resonator are heavily dependent on the chosen resonator magnification. A higher magnification results in a higher output coupling and a better beam quality. But in some configurations, an unstable resonator with a low output coupling in combination with a good beam quality is desirable. In order to reduce the output coupling for a particular resonator, magnification fractions of the outcoupled radiation are reflected back into the cavity. In the confocal case, the output mirror consists of a spherical inner section with a high reflectivity and a flat outer section with a partial reflectivity coating. With the application of the unstable resonator with reduced output coupling (URROC), magnification and output coupling can be adjusted independently from each other and it is possible to get a good beam quality and a high power extraction for lasers with a large low gain medium. The feasibility of this resonator design is examined numerically and experimentally with the help of a chemical oxygen iodine laser.  相似文献   

15.
It is generally acknowledged that product development involves a sequence of decision making under uncertainty, including setting target requirements for a new product, selecting product concept, and developing conceptual and detailed design of a chosen concept. To select a product concept, engineers need to assess the uncertainty of a future market share, market size, and a cost of concept (cost of the final product developed from a concept). This paper proposes a case-based reasoning (CBR) approach to model beliefs about the uncertainty of a cost of concept. The proposed CBR approach consists of storing information about various products in a knowledge-base, defining a new product concept, retrieving a cluster of products in the knowledge-base that are highly similar to the concept, and adapting the cost of the retrieved product to construct a distribution of the cost of concept. This paper illustrates the proposed approach using printers as an example.  相似文献   

16.
Based on the data on the atomic density of a film and degree of its homogeneity during the formation of the interface between 3d transition metals (Cr, Co, Fe, or Cu) and silicon, a new concept of forming a contact between a reactive metal and a semiconductor has been justified. According to this concept, the low-temperature vapor-phase deposition of a metal onto a semiconductor is accompanied by the formation of a two-dimensional nanophase wetting layer of a metal or its mixture with silicon with a thickness of several monolayers, which significantly affects the interface formation and structure. This concept changes a perspective of forming a contact between a metal and a semiconductor substrate: it is necessary to take into account not only the formation of surface phases and clusters and/or the mixing process, but also the effect of elastic wetting of a substrate by the forming phases.  相似文献   

17.
Sasaki K  Kawamura N  Tokumaru H 《Applied optics》2008,47(11):1802-1809
We describe a design of a planar lightwave circuit for parallel information processing using visible light. The circuit serves as a pitch conversion component (PCC) that can align multiple beams close together and easily composes a compact optical system that can project optical spots at a narrow pitch on a certain small plane. From the viewpoint of its application to optical recording, a PCC is designed to have over 50 waveguides according to the fabrication of waveguides for a blue-violet beam. It is analytically confirmed that a PCC contributes to the formation of a multibeam optical recording head with numerous beams.  相似文献   

18.
邓继华  邵旭东 《工程力学》2013,30(10):171-177
利用共旋坐标法提出了一种预应力钢筋混凝土梁非线性分析的混合单元模型,在随转坐标系内,采用分层梁单元来模拟混凝土结构,带初应变的杆单元来模拟预应力钢筋,预应力钢筋杆元和混凝土梁元的变形协调则通过非线性刚臂来实现,通过刚臂单元两端节点位移和力的关系形成预应力钢筋对混合单元刚度矩阵的贡献,从而导出随转坐标系下预应力混凝土梁考虑材料非线性的切线刚度矩阵,几何非线性则由单元随转坐标系到结构坐标系的转换矩阵及其微分来体现,从而获得结构坐标系下混合单元模型的几何与材料双非线性切线刚度矩阵。数个钢筋混凝土及预应力钢筋混凝土梁非线性分析算例表明:所提出的混合单元模型能较好地分析预应力钢筋混凝土梁非线性性能,具有一定的实用价值。  相似文献   

19.
The variational form of a mathematical model of a thermal explosion has been developed based on a variational formulation of a nonlinear problem of stationary thermal conductivity in a homogeneous solid body. The model takes the temperature dependence of the thermal conductivity of a solid body into account. The presented example of quantitative analysis of the model demonstrates a method for finding the combination of parameters for determining a thermal explosion in a plate with an exponential temperature dependence of the thermal conductivity. At the same time, the analysis allows one to identify the number of steadystate temperature distributions inside a body whose energy release intensifies with a temperature increase.  相似文献   

20.
Toyoda M  Araki K  Suzuki Y 《Applied optics》2001,40(30):5295-5303
A technique for transmitting a narrow laser beam from a ground station to a satellite has been developed. The principle of pointing a laser beam to a distant target in a scattering medium by use of a backscattered laser beam image is described. We calculated the intensity distribution of the image by using a typical model of atmospheric coefficients. The method was applied to transmit a laser beam from a ground station to Engineering Test Satellite-VI. The accuracy of pointing the laser beam to the satellite was approximately 10 murad in this experiment.  相似文献   

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