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641.
一个多孔有机织物热湿传递过程的数学模型 总被引:1,自引:0,他引:1
利用多孔介质中的Darcy定律建立了一个多孔有机织物中热湿传递过程的数学模型,并提出了一个描述多孔有机织物中液相水重力与表面张力的对比关系的数H=5gρldcLτlεl1/3/2σcosФε1/3采用Crank—Nicolson方法数值求解了该模型,得到了在相同初始和边界条件下,不同有机材料织物中的热湿传递过程,并给出了多孔有机织物中的水蒸汽的浓度场分布、温度场分布以及纤维中的含水量的分布。计算结果与实验结果是吻合的。 相似文献
642.
R.D.M. Garcia A.M. Yacout 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(5):752-769
The ADO (analytical discrete ordinates) method is used to establish a concise and accurate solution for a multi-layer radiative-transfer problem with Fresnel boundary and interface conditions. A finite plane-parallel medium composed of a number (K) of sub-strata with different material properties is considered to be illuminated by isotropically incident radiation. While a general result is obtained, emphasis in the numerical work is given to computing accurately the currents and the intensities that exit each of the two exterior surfaces. Monochromatic forms (with anisotropic scattering) of the radiative-transfer equation are used, and numerical results are given for several specific cases. The complications introduced by the Fresnel boundary and interface conditions are well resolved, so that the numerical results obtained are thought to define a very high standard. 相似文献
643.
Hone-Ene Hwang 《Optics Communications》2009,282(3):351-4360
The theoretical and numerical analysis in this work show that both surface tilting and translational motion can be simultaneously calculated using the speckle photographic technique by recording consecutive speckle pattern images in two different Fresnel diffraction distances. A simulation example based on the proposed scheme is given to verify the method’s validity and high accuracy of the calculated motion detection. Compared with other previous works the results show that this method is efficient and easy to implement. 相似文献
644.
The modified Beckmann–Kirchhoff scattering theory for surface characteristics in-process measurement
This paper focuses on how the scattering theory can be applied to the analysis of the surface characteristics in an in-process optical measurement. The mean scattered intensity distributions from a surface without and with the additional layers are presented based on the modified Beckmann–Kirchhoff scattering theory. The results show that the introduction of the additional layers only affects rough surfaces. The light scattered from a rough surface under the additional layers seems to be scattered from a bare rough surface with a different surface parameter in the small angle approximation. The experiment is conducted with pixel gray value measurement along the main direction of light scattering stripe to verify the theoretical analysis. The experimental curves can well fit the proposed model, which testifies the correction of the modified Beckmann–Kirchhoff scattering theory. 相似文献
645.
Konstantins Jefimovs Joan Vila‐Comamala Marco Stampanoni Burkhard Kaulich Christian David 《Journal of synchrotron radiation》2008,15(1):106-108
A new type of diffractive X‐ray optical elements is reported, which have been used as beam‐shaping condenser lenses in full‐field transmission X‐ray microscopes. These devices produce a square‐shaped flat‐top illumination on the sample matched to the field of view. The size of the illumination can easily be designed depending on the geometry and requirements of the specific experimental station. Gold and silicon beam‐shapers have been fabricated and tested in full‐field microscopes in the hard and soft X‐ray regimes, respectively. 相似文献
646.
Laws of the iterated logarithm are established for the local U-statistic process. This entails the development of probability
inequalities and moment bounds for U-processes that should be of separate interest. The local U-statistic process is based
upon an estimator of the density of a function of several i.i.d. variables proposed by Frees (J. Am. Stat. Assoc. 89, 517–525, 1994). As a consequence, our results are directly applicable to the derivation of exact rates of uniform in bandwidth consistency
in the sup and in the L
p
norms for these estimators.
Research of E. Giné partially supported by NSA Grant H98230-04-1-0075.
Research of D.M. Mason partially supported by NSA Grant MDA904-02-1-0034 and NSF Grant DMS-0503908. 相似文献
647.
基于红外热释电处理芯片CS9803GP的人体感应开关设计 总被引:2,自引:0,他引:2
信号检测装置采用红外传感器,依据接收人体红外光谱而工作,当人体在其接收范围内活动,自动开启负载,人不离开且在活动,负载持续工作,直至人离开后延时关闭负载,并给出了其完整的硬件电路设计方案与实现方法,其使用性非常好。 相似文献
648.
Bernard King 《Accreditation and quality assurance》2001,6(6):236-243
To facilitate just and sound decisions legal measurements must be reliable. The aim of this paper is to explore how this is
currently achieved and how it might be better done. It considers the different types of legal proceedings, the role of chemical
measurement, level of proof, the different types of chemical measurement, measurement units, the role of government, the chemical
measurement industry and its control, legal metrology and the development of a measurement system based on metrological principles.
It is argued that recent developments provide the basis for a robust support system, that but more needs to be done. It is
also argued that the conventional approach to legal metrology has little place in chemical measurement, but that some controls
are needed in some areas. In particular, a harmonised approach to international measurement standards is advocated.
Received: 29 December 2000 Accepted: 8 January 2001 相似文献
649.
We study optical Fresnel transforms by finding the appropriate quantum mechanical SU(1,1) squeezing operators which are composed of quadratic combination of canonical operators. In one-mode case, the squeezing operator's matrix element in the coordinate basis is just the kernel of one-dimensional generalized Fresnel transform (GFT); while in two-mode case, the matrix element of the squeezing operator in the entangled state basis leads to the two-dimensional GFT kernel. The work links optical transforms in wave optics to generalized squeezing transforms in quantum optics. 相似文献
650.
Michael A. Kouritzin Hongwei Long Wei Sun 《Stochastic Processes and their Applications》2004,110(2):275-294
Herein, we consider direct Markov chain approximations to the Duncan–Mortensen–Zakai equations for nonlinear filtering problems on regular, bounded domains. For clarity of presentation, we restrict our attention to reflecting diffusion signals with symmetrizable generators. Our Markov chains are constructed by employing a wide band observation noise approximation, dividing the signal state space into cells, and utilizing an empirical measure process estimation. The upshot of our approximation is an efficient, effective algorithm for implementing such filtering problems. We prove that our approximations converge to the desired conditional distribution of the signal given the observation. Moreover, we use simulations to compare computational efficiency of this new method to the previously developed branching particle filter and interacting particle filter methods. This Markov chain method is demonstrated to outperform the two-particle filter methods on our simulated test problem, which is motivated by the fish farming industry. 相似文献