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291.
292.
A smart optical liquid level sensor based on the theory of connected vessels is introduced. The Hg cladding optical waveguide (HCOW) is taken as its probe, and the change of liquid level is presented by the change of the HCOW length. Both the theoretical analysis and experiments show that when the waveguide diameter and the light wavelength are certain, the optical power loss decreased linearly with the increase of the HCOW length. By detecting the power loss of HCOW, optimizing the structure of probe and selecting the appropriate apparatus for detection, the real time detection of liquid level with high precision can be got. The experimental results show that the measurement accuracy is 5.2 mm within 10 m liquid level, and its theoretical precision can be up to 0.02%. 相似文献
293.
S. Hudlet M. Saint Jean C. Guthmann J. Berger 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(1):5-10
We propose a very simple method to determine the electrical tip-surface force in Atomic Force Microscopes used to study the
electrical properties of metallic or insulating materials; the analysis of the measurements as well as determination of the
appropriate experimental procedures requiring an analytical model of the tip-surface capacitance. The comparison of force
expressions obtained by this method with those obtained by exact derivation in the case of the sphere-infinite plane system
shows very good agreement. This method is then applied to determine the tip-surface force, the real shape of the tip being
introduced in the derivation. The obtained expression is compared to experimental and numerical data. We emphasize that this
method is very general and can be applied to any axially symmetric capacitor.
Received: 17 June 1997 / Received: 16 September 1997 / Accepted: 7 November 1997 相似文献
294.
A canonical decomposition of two factor spaces obtained from the same variables observed on two populations is considered to obtain statistics of use in the comparison of these spaces. In particular, statistics are derived to test for a common factor space. The asymptotic distributions of these statistics are obtained in a variety of cases using perturbation methods. The methods are applied to a numerical example and results of a simulation are given to indicate the accuracy of the asymptotic results. 相似文献
295.
Sylvain Hudlet Sbastien Aubert Aurlien Bruyant Renaud Bachelot Pierre-Michel Adam Jean-Louis Bijeon Gilles Lrondel Pascal Royer Andrei A. Stashkevich 《Optics Communications》2004,230(4-6):245-251
Apertureless scanning near field optical microscopy techniques have become a common way of studying surface samples. By using a nano-probe that scatters the electromagnetic non-propagative waves emerging from a given sample, this microscopy provides optical images with a resolution beyond the diffraction limit. Despite a great diversity of works covering a wide variety of physical domains, the formation of the images obtained is not yet fully understood. The purpose of this letter is to assess the influence of the tip position and imposed oscillation of the tip in apertureless SNOM when a background field is added to the scattered near field. We propose a simple analytical model which enables us to account for the experimental results and explains how, depending on the experimental conditions, the near field signal can totally disappear or, on the contrary, be greatly enhanced. 相似文献
296.
本文参考有关统计资料,对我国新颁公路桥规JTJ023-85中钢筋混凝土构件承载能力的可靠指标进行了计算分析,并讨论了影响构件可靠度指标的几个主要因素。采用的方法是一种近似概率计算方法——一次二阶矩法,即只考虑随机变量的平均值和标准差两统计参数,对设计表达式进行线性化处理。结果表明,延性破坏构件在荷载组合G+Q_1下β平均值为3.6,在C+Q_2下β平均值为2.8;脆性破坏构件,则分别为4.1和3.3。这是新规范所反映的钢筋混凝土构件可靠度的基本水平。另外在某些荷载效应比值下提高了荷载安全系数和对脆性破坏构件考虑了工作条件系数,都较为合理。但构件在不同荷载情况下尚不能得到比较一致的可靠度。抗力和荷载效应的分项系数以及荷载的标准值还需进一步研讨。 相似文献
297.
We exhibit a newansatz for the solution of the homogeneous three-dimensional time-dependent wave equation in spherical coordinates of the form Φ(r,t)=Y(θ, φ)(I(r)+G(g)), whereg ≡ct/r. FunctionG(g) has explicit solution in terms of three independent nonperiodic functionss
ℓ,t
ℓ,u
ℓ (s
ℓ andt
ℓ
are related to the associated Legendre functions of the first and second kinds).G(g) is nonperiodic and may be cast as a superposition of incoming and outgoing waves. To obtainG(g), we solved a nonhomogeneous associated Legendre equation (this solution, to our knowledge, is also new).G(g) may prove useful in many microscopic and macroscopic problems, representable by homogeneous wave equations. 相似文献
298.
In this work we present a very fast and parsimonious method to calculate the centre coordinates of hyperbolic components in the Mandelbrot set. The method we use constitutes an extension for the complex domain of the one developed by Myrberg for the real map x ] x2−p, in which, given the symbolic sequence of a superstable orbit, the parameter value originating such a superstable orbit is worked out. We show that, when dealing with complex domain sequences, some of the solutions obtained correspond to the centres of the Mandelbrot sets hyperbolic components, while some others do not exist. 相似文献
299.
本文采用多元统计分析中的主成分分析方法改进型,对城市工业企业的经济效益给予综合评判,然后又对综合评判系数采用系统聚类分析方法对其作了分类,用以找出各类城市的优势和差距,便于针对性地制定提高经济效益的对策. 相似文献
300.
在由S和D核子关联对构成的原子核集体运动态中,存在由辛弱数混合造成的伪态成份. 给出了计算这种伪态成份的公式,并进行计算和讨论. 相似文献