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1.
Diamond films with different thicknesses were deposited on flat and curved molybdenum substrate by the microwave plasma chemical vapour deposition (MPCVD) method. Scanning electronic microscopy, atomic force microscopy and Raman spectroscopy were employed to characterise the morphology, the surface roughness and the composition of the films, respectively. A NanoTest system was used for hardness, elastic modulus and nanoimpact tests. The curved surface and ductility of the molybdenum substrate allow large deformation for the thinner films. The substrate has less effect on impact for the thicker film, the deformation of which is mainly determined by the film composition. Under a load of 50 mN and 75 cycles, less deformation occurred for the 22 μm thick film on the curved molybdenum substrate.  相似文献   

2.

The equilibrium configuration of soap films in a tetrahedral frame is well known, and a study is reported here of the displacement of the tetrahedral vertex formed at the junction of the Plateau borders between the films. Applying a force to this junction causes an increase in soap film area, and hence surface energy, which is modelled both theoretically and numerically. In the present work, this force is conceived as being due to the displacement of a small particle at the centre of the vertex and the energy dependence of the configuration on both the size of the particle and the magnitude of the displacement is calculated. The results underline the importance of the curvature of the films in any detailed analysis of the suspension of particles in a foam, as, for example, in the industrial process of foam flotation. The results are relevant also to problems of foam drainage and stability.  相似文献   

3.
CeO2-doped diamond-like carbon (DLC) films with thicknesses of 180–200 nm were deposited by unbalanced magnetron sputtering. When the CeO2 concentration is in the range 5–8%, the residual compressive stress of the deposited films is reduced by 90%, e.g. from about 4.1 GPa to 0.5 GPa, whereas their adhesion strength increases. These effects are attributed to the dissolution of CeO2 within the DLC amorphous matrix and a widening interface between the DLC film and the Si substrate, respectively.  相似文献   

4.
本文介绍由塔斯基的立体几何导出的球态语义学,并将其应用于自然语言中的动词体现象。球态语义学特别适合应用于英语的进行体。这种方法有以下优点(i)它扩展了区间式语义,并同时避免了其缺陷,(ii)它解决了未完成体难题,(iii)它的解决方法无需诉诸最终结果策略。逻辑方法一般被认为难于处理自然语言的动词体问题。基于点的时间结构以及建立在该结构之上的经典普莱尔时态逻辑([18])太弱了。而基于区间的时态语义则缺乏足够的表达力,并且难以解释进行体([4,8]).本文给出一种新的基于球上整体-部分关系概念的模型和时态语义。这种球态语义学建基于塔斯基1927年引入的立体几何之上。与基于点和基于区间的语义不同,在球态语义学中很多动词体区分都由统一的逻辑方法刻画。在一个由封闭球构成的论域中,可达关系由相切性概念给出。相应地,我们可定义外切、内切、外径、内径以及同心等基本概念。与区间式语义不同,球是论域的初始概念,球态语义学不是在时间段而是在球中对事件赋值。因此,仅将时间区间作为初始概念而不承认其端点初性性的问题不复存在。英语中的进行体由球上的连续行动来刻画。行动是非终止的,只要球没有由外切相离。相应地,外切相离刻车动作完成。我们区分在均匀球和非均匀球中发生事件的整体-部分关系。非持续动作视为直径为零的同心球。球态语义学根据动作或执行完成的时刻来定义时间概念,其中不需要时间端点的概念。在保持与基于区间的时间模型类似的基础上,球态语义学暗示了一种关于可能世界的定性概念,并且它有利于解决时间的循环概念问题。  相似文献   

5.
ABSTRACT

The basic mechanisms governing the process of cracking of single-layer brittle films have been extensively explored through both simulations and experiments. However, the role that an adhesive interlayer plays in the cracking of the overlying brittle film remains unclear. By performing three-point bending experiments, we observed that the insertion of a 100?nm thick Ti interlayer changed the cracking behaviour of TiN films from a continuous pattern to a discontinuous pattern. The slight change in the microstructure of the film and the increase in film thickness arising from the addition of the Ti interlayer are unlikely to cause the observed cracking morphology. The combination of the different interface between the Ti and the steel substrate and the fracture of the Ti interlayer are responsible for the transition in the TiN film cracking morphologies.  相似文献   

6.
Drawing on two years of ethnographic fieldwork in Egypt focused on organ transplantation, this paper examines the ways in which the “scientific” criteria of determining death in terms of brain function are contested by Egyptian doctors. Whereas in North American medical practice, the death of the “person” is associated with the cessation of brain function, in Egypt, any sign of biological life is evidence of the persistence, even if fleeting, of the soul. I argue that this difference does not exemplify an irresolvable culture clash but points to an unsettling aspect of cadaveric organ procurement that has emerged wherever organ transplantation is practiced. Further, I argue that a misdiagnosis of the problem, as one about “religious extremism” or a “civilizational clash,” has obfuscated unresolved concerns about fairness, access, and justice within Egyptian medical spheres. This misdiagnosis has led to the suspension of a cadaveric procurement program for over 30 years, despite Egypt’s pioneering efforts in kidney transplantation.  相似文献   

7.
A hill of salt in the Belfast docklands shimmers like an iceberg at sea. A laminated photograph of Sergei Eisenstein drifts in front of a camera as it moves amongst the streets of Mexico City. A grey mist hovers across Stockholm, obscuring the city behind it. These three images are from a sequence of essay films directed by Mark Cousins. In this paper, I discuss the work of Cousins in terms of its floating aesthetics and mobile methodologies. Throughout his films, Cousins's camera drifts through urban spaces, tracing the images and sounds of cityscapes that typically escape us. The films are attentive to the colours infused and refracted through their urban environments, prompting an understanding of cities as studies in fleeting colour, light and luminosity. I engage with Japanese aesthetic theories in order to draw out resonances between the historical art of urbanising Japan and the city scenes of Cousins's films. This paper offers a reflection on the capacity of Cousins's films to evoke an understanding of cities as lively, sensuous and evanescent harbours of a floating world.  相似文献   

8.
Cosmopolitanism and statism represent the two dominant liberal theoretical standpoints in the current debate on global distributive justice. In this paper, I will develop a feminist argument that recommends that statist approaches be rejected. This argument has its roots in the feminist critique of liberal theories of social justice. In Justice, Gender, and the Family Susan Moller Okin argues that many liberal egalitarian theories of justice are inadequate because they assume a strict division between public and private spheres. I will argue that this inadequacy is replicated in statist approaches to global justice. To demonstrate this, I will show how an analogue of Okin's critique of Rawls's A Theory of Justice can be extended to his The Law of Peoples. I will conclude that statist theories inevitably assume a strong divide between public and private spheres and that by doing so they allow for situations marked by gross injustice which anyone concerned with the welfare of the world's most vulnerable should find unacceptable.  相似文献   

9.
We report the twin-coupled multi-oriented domain structures in the epitaxial BZT20 (20%Zr) films grown on the (001) MgO substrate using pulsed-laser deposition. Transmission electron microscopy shows that the film consists of an epitaxial layer of pseudo-cubic perovskite structure and a nanopillar layer of multi-oriented twin domain structures near the surface. Four types of the twin domains were formed in the nanopillar layers by coherently joining their {111} with the epilayer and aligning their ?110? directions parallel to the ?110? axes of the epilayer. A non-uniform polarization switching behavior was observed due to the formation of such complex structure in the BZT20 films.  相似文献   

10.

We report the generation of fullerenes and nanotubes using an arc discharge on graphite in a high-pressure nozzle. The vapour from the arc is quenched via collisions with helium gas, forming carbon clusters within a localized highpressure region. The carbon molecules are entrained in the gas jet as it expands into the vacuum and deposited onto a silicon substrate in a low-pressure (6 mT) environment. Mass spectroscopy measurements of the plasma reveal the presence of C molecules in the expanding plume. Microstructural examination of films deposited using this method revealed clustered regions of larger fullerenes and nanotubes surrounded by an amorphous matrix. Films containing fullerenes and nanotubes were found to be significantly harder and more elastic than amorphous carbon films deposited under identical parameters but without conditions for fullerene and/or nanotube formation.  相似文献   

11.

Al-Cu-Fe-Cr quasicrystalline thin films were grown on atomically flat Al 2 O 3 sapphire (0001) substrates by single-target magnetron sputtering followed by annealing. A decagonal phase with the tenfold axis A 10 parallel to the substrate surface normal was observed. The epitaxial decagonal film had two different unique orientations: a twofold P axis A 2P and a twofold D axis A 2D parallel to of the substrate. These two configurations were explained using a coincidence reciprocal lattice planes model for the interface energy. We show that this classic approach for crystal-crystal epitaxy can be applied to quasicrystal-crystal systems.  相似文献   

12.

The critical current densities of superconducting thin films and their dependence on the film structural characteristics has been a major research interest for more than a decade. Controlling this relationship is crucial if large-scale high-quality YBa 2 Cu 3 O 7 (YBCO) tapes are to be produced. Two major keystones of information have been established in this field. Firstly, there is a direct relationship between the critical current density and the grain-boundary angle in polycrystalline YBCO films. Grain boundaries with a mismatch angle higher than 5° usually result in reduced critical current densities. This detrimental effect of large-angle grain boundaries to the quality of YBCO films has been attributed to strain fields resulting from such grain boundaries. Secondly, the quality of the YBCO film can be enhanced by straining its lattice in specific direction. Here, we report, for the first time, direct experimental results coupling local grain orientation and local strain maps of thin YBCO films deposited on a (001) biaxially textured nickel substrate. These results were correlated to the quality of the film and showed how grain structure in the nickel substrate affects the grain structure in the YBCO films even in the presence of several buffer layers. More importantly, the data show that highquality films with high critical current densities can be produced, in spite of large-angle grain boundaries, if the film is compressed in the range of 0.5% strain normal to the a axis.  相似文献   

13.
A variation of the conditional discrimination procedure defines relations between stimuli (for example, gestural signs and their referents), and it has been used to study language comprehension in California sea lions. The animals followed instructions given by a trainer's gestures designating properties of size, brightness, and location (adjectives), types of objects (nouns), and actions (verbs). The signs can be combined and recombined according to a conditional sequence or syntax. In this study, we sought to determine whether adjectives for size had an absolute meaning, that is, small and large, as well as a comparative meaning, that is, smaller and larger. A sea lion, Rocky, was given experience with signs designating standard small and large spheres in commands like LARGE BALL MOUTH. On transposition tests, the small ball was removed and the previously designated large ball was paired with an even larger one. The results showed that the adjectives had both an absolute and a relative meaning. Object choices and searching behavior revealed that the sea lion processed information about the relation of size as well as about the specific characteristics of the sizes of spheres that instantiated the relations.  相似文献   

14.
This study was designed to develop a computerized test to assess gender roles. This test is presented as a decision-making task to mask its purpose. Each item displays a picture representing an activity and a brief sentence that describes it. Participants have to choose the most suitable sex to perform each activity: man or woman. The test (Gender Roles Test, GRT-36) consists of 36 items/activities. The program registers both the choices made and their response times (RTs). Responses are considered as stereotyped when the chosen sex fits stereotyped roles and non-stereotyped when the chosen sex does not fit stereotyped roles. Individual means (RTs) were computed for stereotyped and non-stereotyped responses, differentiating between domestic and work spheres. A "D" score, reflecting the strength of association between activities and sex, was calculated for each sphere and sex. The study incorporated 78 participants (69% women and 31% men) ranging from 19 to 59 years old. The results show that: (a) reading speed does not explain the variability in the RTs; (b) RTs show good internal consistency; (c) RTs are shorter for stereotyped than for neutral stimuli; (d) RTs are shorter for stereotyped than for non-stereotyped responses. Intended goals are supported by obtained results. Scores provided by the task facilitate both group and individual detailed analysis of gender role, differentiating the gender role assigned to men from that assigned to women, at the domestic and work spheres. Obtained data fall within the scope of the genderology and their implications are discussed.  相似文献   

15.

A detailed reflection high-energy electron diffraction study of the first stages of the niobium growth on (1120)s sapphire is presented for several substrate temperatures. It is shown that the niobium film exhibits an hexagonal surface structure when the deposited thickness is smaller than a critical value, which, depending on the substrate temperature, varies between 5 and 15 A. For thicknesses larger than this critical thickness, the surface hexagonal structure relaxes to the (110) bcc niobium structure. The hexagonal surface structure is observed for high substrate temperatures (820-410oC) but does not appear when the substrate temperature is 270oC. The epitaxial relationships between the substrate, the surface hexagonal structure of niobium and the cubic niobium phase are presented.  相似文献   

16.
Expert and novice radiologists were given films accompanied by clinical histories that supported a diagnosis either of bronchiolitis or of normal. To provide a plausible task context, some films were radiologically unambiguous and were accompanied by histories consistent with them. For a set of radiologically difficult films from confirmed normal or bronchiolitis patients, fictitious normal or abnormal histories were counterbalanced with the films. The clinical histories affected ratings both of diagnosis and of features present on the difficult films. Thus, uncertainty about individual features evidently was affected by history, and features did not act as an independent source of information. The dependence of feature calls on an overall judgment was also suggested by intra-observer agreement in another study in which an explicit diagnosis was not requested. It is unclear whether the history increased discrimination between normal and abnormal films, or indiscriminately added evidence for or against the disease. Factors are discussed that make it appropriate for feature identification to be partially dependent on category identification.  相似文献   

17.
Peter Barker 《Synthese》1990,83(2):317-323
I argue that Copernicus accepted the reality of celestial spheres on the grounds that the equant problem is unintelligible except as a problem about real spheres. The same considerations point to a number of generally unnoticed liabilities of Copernican astronomy, especially gaps between the spheres, and the failure of some spheres to obey the principle that their natural motion is to rotate. These difficulties may be additional reasons for Copernicus's reluctance to publish, and also stand in the way of strict realism as applied to De Revolutionibus, although a realistic astronomy may be envisioned as a goal for Copernicus's research program.  相似文献   

18.
In three experiments, difference thresholds (dLs) and points of subjective equality (PSEs) for three-dimensional (3-D) rotation simulations were examined. In the first experiment, observers compared pairs of simulated spheres that rotated in polar projection and that differed in their structure (points plotted in the volume vs. on the surface), axis of rotation (vertical, y, vs. horizontal, x), and magnitude of rotation (20 degrees-70 degrees). DLs were lowest (7%) when points were on the surface and when at least one sphere rotated around the y-axis and varied with changes in the independent variables. PSEs were closest to objective equality when points were on the surface of both spheres and when both spheres rotated about the x-axis. In the second experiment, subjects provided direct estimates of the rotations of the same spheres. Results suggested a reasonable agreement between PSEs for the indirect-scaling and direct-estimate procedures. The third experiment varied sphere diameter (and therefore mean linear velocity of stimulus elements) and showed that although rotation judgments are biased by mean linear velocity, they are not likely to be made solely on the basis of that information. These and past results suggest a model whereby recovery of structure is conducted by low-level motion-detecting mechanisms, whereas rotation (and other) judgments are based on a higher level representation.  相似文献   

19.
Ordered nanostructured cobalt-doped nickel oxide films were prepared on a conducting glass substrate via the sol–gel dip-coating method. X-ray diffraction analysis shows the films to be amorphous. Field-emission scanning electron microscope images showed well-defined, ordered grains with pores in between them. Supercapacitor behaviour was studied using cyclic voltammetry. A maximum specific capacitance of 1982?F/g at a scan rate of 5?mV/s with 1?M KOH was obtained for 5?wt% of cobalt-doped nickel oxide films. AC impedance analysis showed that the solution resistance was R s?=?27?Ω and the charge transfer resistance R ct?=?20?Ω.  相似文献   

20.
This article compares the ways in which the classic Western philosophical division between the private and public spheres is challenged by an apparently disparate pair of thinkers—Confucius and Jane Addams. It is argued that insofar as the public and private distinction is that between the sphere of the family and that outside of the family, Confucius and Addams offer ways of rethinking that distinction. While Confucius endorses a porous relation between these realms, Addams advocates a relation that fosters reconstructive transformation of each the private and public spheres. Because Confucius and Addams both challenge the idea of a rigid separation between the private and public, while at the same time differing from one another in important ways, a comparative engagement of their views is performed, with the suggestion that Confucians might glean very much from Addams, while contemporary feminists might do the same from both she and Confucius.  相似文献   

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